The correct answer is b) mutualism.
Mutualism is a type of symbiotic relationship where both organisms involved benefit from the interaction. This can include various forms of partnerships, like bees pollinating flowers while obtaining nectar for food. In contrast, parasitism, where one species benefits at the expense of another, and commensalism, where one benefits while the other is unaffected, do not fit the criteria of both species benefitting. Predation, on the other hand, involves one organism hunting and consuming another, which is not a mutually beneficial relationship either.